Method of producing metals or alloys



Patented Apr. 14, 1925.

' UNITED STATES CARL ROBERT SCHBDEDER, OF HOIBOKEN, NEW ERSEY.

METHOD OF PRODUCING METALS R ALLOYS.

No Drawing.

To'all whom it may concern.

Be it known that I, CARL R. SoHRoEnEn, a citizen of the United States, and resident of Hoboken, in the county of Hudson and 6 State of New Jersey, have invented certain new and useful Methods of Producing Metals or Alloys, of which the following is a specification.

The invention relates to the reduction of metals or metallic alloys from ores or comounds which are comparatively high in impurities which would be objectionable or deleterious to the 'metalliferous product, and

. has for its object to produce the desired met- 1 als or alloys in relatively pure, or at least commercially'acceptable condition, by so effecting the reducing reaction that the desired metalliferous values will be reduced selectively with respect to the impurities or :0 undesirable reducible elements, so that the latter will be practically eliminated or ocour only in permissible amounts in theultimate product. It has been found that by properly regulating the quantity of the re- 2 ducing agent, ,in accordance with the rela- 'tive quantities or proportions of the desirable and undesirable elements occurring in the treated ores or com ounds, the reducing reaction may be carrie out in such manner so asto reduce the desired metal or alloy without efiecting any material reduction of the undesired or objectionable components so that the latter will be either substantially eliminated from the ultimate product, or 35, will occur in such small proportions therein as to constitute no serious impairment of the commercial value of'the ultimate metal -,oralloy'. In the production of metals from ores,

40 oxides or other compounds, by the reaction of a'reducing agent, the oxygen of the ore or oxide combines with the reducing agent or some reactive elements thereof, and libcrates the metal. When the reaction is produced by the aluminothermic method it has always been found necessary, heretofore, in order to effect the production of the metals relatively low in impurities, that the ore or oxide used be also low in these impurities,

and it was usual, except in cases "involving the use of rather pure natural ores and oxides, to purify the ores and oxides by one or more of the well known mechanical, me g a r chemical methods, which Application filed November 22, 1919. Serial No. 339,905.

naturally required the-expenditure of considerable time and monetary cost, and was usually accompanied by loss in the quantity of the metallic values recovered. For example, in the manufacture of high percentage tungsten alloys by the aluminothermic process the success of the reaction required the employment of relatively pure and expensive raw material, or an artificially prepared tungsten compound in which the preparatory treatment was effected, at a cost of time and money, to eliminate any undesirable elements or compounds which would impair the ultimate product. The conditions which apply to the production of metallic tungsten b the reduction process also exist in the app ication of the process to the production of tungsten alloys, such as ferro-tungsten, from practically all kinds of tungsten ores, such as scheelite, Wolfram? ite, ferberite, and others, which nearly always contain such impurities as silicon, manganese, phosphorus, sulphur, etc., which must be practically eliminated or reduced to such proportions that they will be innocuous in the ultimate ferro-tungsten alloy.

I-have discovered that it is possible to control the proportions of the impurities in the final metalliferous product by a direct variation of the amount of the reducing agent employed, and while the invention finds particularly eflicacious application to the reduction of metallic compounds by the aluminothermic method, it is not limited to such method, but is applicable to other deducing reactions in which the quantities of the reducing agent can be controlled and regulated in accordance with the proportions of the desired metallic values occurring in'the compounds treated, the reactions occurring by what may be termed a selective reduction- It has been found that in compounds containing several metals not all of the metals are reduced simultaneously, but that the reducing action is sequential or successive depending upon the reactive energy required to split the compounds 'into their elements, such, for instance, as reducing oxides into metal and oxygen, chlorides into metal and chlorine, etc. The reducing or reactive agent follows the lines of least resistance and acts upon the more responsive metallic compounds first, and the less re-. sponsive in sequence, so that if just suflicient quantity of the reducing agent is supplied to the bulk of ore or metalliferous compounds to be treated to efiect the desired reaction with the more responsive metals, these latter will be reduced to metallic state before,any material reducing action takes place between the reducing agent and the less responsive metallic values or other impurities, which it is desired to exclude from the ultimate product, so that the desired metallic values, either in the form of a single metal, or an alloy of metals, may be re covered with only a relatively small proportion of the impurities or undesirable elements admixed therewith and which'are not sufficient to impair the commercial value of the final product, the major portion of the impurities remaining in the slag and being carried off therewith.

For example, it has been found that tungstic oxide and iron oxide are readily reduced and when reduction is effected by the aluminothermic method these two oxides will be reduced to ferro-tungsten before any appreciable amount of the other oxides usually found in ores and compounds containing these metals, such as silica and manganese oxide, are attacked, and, by regulating the quantity of aluminum employed to just sufficient to reduce all of the tungsten and iron compounds present, the reducing operation will be suspended when this re sult has been effected, and most of the silica and maganese will remain in the slag. Of course, it is not feasible to reduce all of the tungstic oxide and iron oxide in an ore or compound before any of the remaining metallic compo-unds begin to react with the aluminum, but I have found that it is possible to effect a reduction of 80%- of the tungstic oxide in the reduction mixture before as much as 10% of the silica and manganese oxide has reacted. It is therefore possible to reduce tungsten ores containing as high as 7% manganese oxide and 7% silica by means of the aluminothermic reaction, and still produce a very high ferrotungsten alloy which contains considerably less than 1% manganese and 1% silicon,

an amount which is permissible in the trade.

It is obvious that in redueingan ore or compound so high in impurities the re cm'ery in metallic tungsten is fractionally lower than in the case of pure raw material, such as tungstic oxide or calcium tungstatc, but the loss is very small andamounts to only a fraction of the cost of any cfiectire preparatory treatment of the ore to eliminate the impurities before the reduction is efiected.

In order to arrive at the proper propor tions of the vreducing agent to be employed,

I regulate the quantity of the reducing agent,

relative to the amounts or proportions of the desired metal or metals. For example, if" the proportions by weight of tungstic oxide and iron oxide in a given ore or mixture are known, the amount of aluminum required to produce a satisfactory recovery of ferro-tungsten may be readily arrived at either by calculation or by running a. test on a small proportion of the compound or ore, the results of which will indicate at once whether the resultant ferro-tungsten is satisfactory and sufliciently low in impurities to be commercially acceptable. After this condition has been established and the proper proportion of the reducing agent determined, the entire lot of ore from which the test sample was taken, is reduced under-the same conditions. All operations, except the preparation of the reduction mixture, are carried out in the same manner as the usual aluminothermic reactions for the recovery of metallic values, with the assurance that the resultant ferro-tungsten alloy will contain only permissible proportions ofthe obj ectionableelements, such as silicon and manganese. All other impurities, such as phosphorus, sulphur, etc., may be present within the same limitations as are required for the production of ferro-tungsten in the electric furnace or for the pro- 95 duction of tungsten powder by means of the alkali fusion process.

The success and efficiency of the method as described may be illustrated by taking a concrete example of one of the well known 1 0 tungsten ores containing the following percentage of metallic oxides:

Per cent. WOr,- 69.02 r s10, i 3.13 MnO 7.50 FeO 21.39

.and the third producing a ferro-tungsten in which the proportions of manganese and silicon. were well within the permissive commercial limits.

In the first case, 25.25 pounds of aluminum per pounds of ore were used and an analysis of the alloy showed the following proportions:

Percent. Tungsten 70 Iron 21 Silicon 1.8 Manganese 7.2

Such an alloy would probably have a very limited application in the trades, because of the relatively high percentages of the im purities or objectlonable elements silicon and manganese.

In the second run 21.5 pounds of aluminum per'.100 -pounds of ore were used and 1 the analysis showed the following proportions of metallic constituents in the resultant alloy:

' Percent. Tungsten 78 Iron 17 -Silicon 1.13 Manganese 2.23

This clearly demonstrates that one of the objectionable impurities, to wit, manganese, has been partially eliminated. This was accompanied, of course, by a slight loss in efliciency in the tungsten content recovery.

In the third case, 21 pounds of aluminum per 100 pounds of oreqvere used and the resultant alloy showed tungsten 78%, iron 19%, silicon 0.8%, manganese 0.32%, in which the proportions of silicon and manganese are well within permissive limits and the roduct being an alloy not limited in its use ause of'the presence of impurities. This last result was accomplished without any material loss in the efliciency of the' tungsten recovery.

It will therefore be apparent that, by employing the aluminothermic method of reduction in connection with the particular ore referred to, it was possible to eliminate a very large proportion of the objectionable elements without any of the ordinary preliminary treatment required in connection with ores of this general character andto produce a commercially acceptable ferrotungsten direct from the ore. It will also be apparent that, by properly selecting and apportioning the amount of the reducing agent employed, a very wide range of ores may be treated to produce ferro-tungsten of the same degree of purity, and the proc- 1 ess is, therefore, not limited to ores which arecarefully selected as would be the case even when the latter are subjected to premetal or metals to be recovered, that the reducing action will be confined largely between the desired metallic values and the reducing agent and the action of the latter on the undesired elements will be so limited that the proportions of the impurities in the resultant metal or alloy reduced will be unimportant.

What I claim is:

1. The method of producing metals or alloys from compounds comparatively high in impurities, which comprises effecting the aluminothermic reaction in the compound, and so regulating the amount of aluminum as to substantially restrict the reducing action to the desired metalliferous material.

2. The method of producing ferro-tungsten from compounds comparatively high in impurities, which comprises effecting a re- .action between the compound and 'a reducing agent, and so regulating the amount of said reducing agent as to substantially restrict the reaction to tun n.

3. The method of producing ferro-tungsten from compounds comparatively high in impurities, which comprises effecting the aluminothermic reaction in the compound, and so regulating the amount of aluminum as to substantially restrict the reducing action to the iron and tungsten.

Signed at Jersey City, in the county of Hudson and State of New Jersey, this 19th day of November A-. D. 1919. V

CARL ROBERT SCHROEDER.

the reduction of the iron and 

